Many types of woodworking tools, milling tools, shop equipment and the like have as a common characteristic a head that is rotated and/or reciprocated or orbited about a path, while it has at least one cutter or other knife-like or abrading-type working surface or working edge means adjustably attached to the head. Most generally, each working surface or edge means is mounted for compound-direction adjustment relative to the head. Accordingly, accurate adjustment generally involves something more than, for instance, merely turning one crank to move an edge radially inwards or outwards by a uniform amount along the whole length of the cutting edge. In fact, means for compound-directional adjustment is provided particularly because it is needed in order to uniformly position the working edge or surface. That is, for example, on a machine where it is possible to move a cutting edge radially outwards, there often may be a means for adjusting the amount of radial extension of one end of the cutting edge relative to the other, in order to prevent the cutting edge, when the head is rotated, from cutting too deeply into the work at one end and/or not deeply enough into the work at the opposite end.
One can dream all too easily of wanting exotic devices provided on one's tools of this sort, for instance electric-eye or laser-type devices that one could use for automatically adjusting the working edges or surfaces by pushing some buttons or entering a program into a controller. And certainly it would be feasible to go to the expense of such solutions for some expensive industrial applications, but for the widespread practical situation adjustment has been more a matter of cut and try, of naked-eye adjustments made with the aid of gauging blocks, calipers, rulers, squares and other jigs.